5.3 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| North American DC-3 | 1/5 | https://en.wikipedia.org/wiki/North_American_DC-3 | reference | science, encyclopedia | 2026-05-05T13:21:41.394188+00:00 | kb-cron |
The DC-3 was one of several early design proposals for the NASA Space Shuttle designed by Maxime Faget at the Manned Spacecraft Center (MSC) in Houston. It was nominally developed by North American Aviation (NAA), although it was a purely NASA-internal design. Unlike the design that eventually emerged, the DC-3 was a fully reusable launch vehicle two-stage-to-orbit spaceplane design with a small payload capacity of about 12,000 lb (5,400 kg) and limited maneuverability. Its inherent strengths were good low-speed handling during landing, and a low-risk development that was relatively immune to changes in weight and balance. Work on the DC-3 program ended when the US Air Force joined the Shuttle program and demanded a much greater "cross-range" maneuverability than the DC-3 could deliver. There were also serious concerns about its stability during re-entry, as well as heating conditions on its straight wings. NAA eventually won the Shuttle Orbiter contract, based on a very different design from another team at MSC.
== History ==
=== Background === In the mid-1960s the US Air Force conducted a series of classified studies on next-generation space transportation systems. Among their many goals, the new launchers were intended to support a continued crewed military presence in space, and so needed to dramatically lower the cost of launches and increase launch rates. Selecting from a series of proposals, the Air Force concluded that semi-reusable designs were the best choice from an overall cost basis, and the Lockheed Star Clipper design was one of the most-studied examples. They proposed a development program with an immediate start on a "Class I" vehicle based on expendable boosters, followed by a slower development of a "Class II" semi-reusable design, and perhaps a "Class III" fully reusable design in the further future. Although it is estimated that the Air Force spent up to $1 billion on the associated studies, only the Class I program proceeded to development, as the X-20 Dyna-Soar, which was later cancelled. Not long after the Air Force studies, NASA started studying the post-Project Apollo era. A wide variety of projects were examined, many based on re-using Apollo hardware (Apollo X, Apollo Applications Program, etc.) Flush with the success of the Moon landings, a series of ever-more ambitious projects gained currency, a process that was considerably expanded under the new NASA director, Thomas O. Paine. By about 1970 these had settled on the near-term launching of a 12-man space station in 1975, expanding this to a 50-man "space base" by 1980, a smaller lunar-orbiting station, and then eventually a crewed mission to Mars in the 1980s. NASA awarded $2.9-million study contracts for the space stations to North American and McDonnell Douglas in July 1969. Almost as an afterthought the idea of a small and inexpensive "logistics vehicle" for supporting these missions developed in the late 1960s. George Mueller was handed the task of developing plans for such a system, and held a one-day symposium at NASA headquarters in December 1967 to study various options. Eighty people attended and presented a wide variety of potential designs, many from the earlier Air Force work, from small Dyna-Soar like vehicles primarily carrying crew and launched on existing expendable boosters, to much larger fully reusable designs.
=== ILRV === On 30 October 1968 NASA officially began work on what was then known as the "Integral Launch and Re-entry Vehicle" (ILRV), a name they borrowed from the earlier Air Force studies. The development program was to take place in four phases; Phase A: Advanced Studies; Phase B: Project Definition; Phase C: Vehicle Design; and Phase D: Production and Operations. Four teams were to participate in Phase A; two in Phase B; and then a single prime contractor for Phases C and D. A separate Space Shuttle Main Engine (SSME) competition was to run in parallel. NASA Houston and Huntsville jointly issued the Request for Proposal (RFP) for eight-month Phase A ILRV studies. The requirements were for 5,000 to 50,000 lb of payload to be delivered into a 500 km altitude orbit. The re-entry vehicle should have a cross range of at least 450 miles, meaning that it could fly to the left or right of its normal orbital path. General Dynamics, Lockheed, McDonnell-Douglas, Martin Marietta, and (the newly named) North American Rockwell were invited to bid. In February 1969, following study of the RFPs, Martin Marietta's entry was dropped, although they continued work on their own. The other entries were all given additional Phase A funding. Supported by Paine's ambitious plans, in August 1969 the ILRV program was re-defined to be a "maximum effort" design, and only fully reusable designs would be accepted. This led to a second series of Phase A studies. The designs that were returned varied widely, meeting the huge payload range specified in the original RFP. Two basic fuselage designs seemed to be the most common; lifting body designs that offered high cross-range but limited maneuverability after re-entry, and delta-winged designs that reversed these criteria.
=== DC-3 ===